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Drool makes grass safe to eat

Drool may be gross, but it’s a powerful fungus fighter, according to new research. Biologists collected saliva samples from sedated moose (Alces alces) and European reindeer (Rangifer tarandus). They also grew red fescue, a grass that the two animals commonly munch on in Sweden. The scientists then conducted two experiments. They added the saliva to test tubes teeming with colonies of the fungus Epichloë festucae, which often lives within the grass and helps produce toxic chemicals to ward off ravenous grazers like livestock, and also to recently trimmed grass infected with the fungus. The latter simulated how grass gets ripped and doused with slobber when it’s been chomped on by a herbivore. Compared with fungi samples treated with water, moose and reindeer saliva slowed the growth of the fungi. When applied to clipped grass, moose drool reduced the production of the toxic chemicals between 41% and 70%, whereas grass that was not treated with saliva actually doubled in its release of toxic chemicals, according to a study published online today in Biology Letters. The results suggest that large mammalian herbivores have evolved the ability to fight back against plant defenses to either detoxify their greens or curb venomous chemical production.